docs: def _get_stddevs(self, C, stddev_types, num_sites):
  
          """
          Return total standard deviation as described in paragraph 5.2 pag 200.
          """
  
          # interevent stddev
          sigma_inter = C['tau'] + np.zeros(num_sites)
          # intraevent std
          sigma_intra = C['sigma'] + np.zeros(num_sites)
          std = []
  
          for stddev_type in stddev_types:
              if stddev_type == const.StdDev.TOTAL:
                  # equation in section 5.2 page 200
                  std += [np.sqrt(sigma_intra**2 + sigma_inter**2)]
              elif stddev_type == const.StdDev.INTRA_EVENT:
                  std.append(sigma_intra)
              elif stddev_type == const.StdDev.INTER_EVENT:
                  std.append(sigma_inter)
  
          return std